The field of the present invention relates to trailer hitches. In particular, a lockbox is shown and described herein for securing a coupler of a trailer hitch.
A wide variety of hitching post and security devices are available for trailer couplers or hitches. Some of these are described in, e.g.:    U.S. Pat. No. 3,857,575 entitled “Security trailer hitching post” issued Dec. 31, 1974 to Lee;    U.S. Pat. No. 4,032,171 entitled “Trailer hitch locking device” issued Jun. 28, 1977 to Allen et al;    U.S. Pat. No. 4,141,569 entitled “Theft prevention device” issued Feb. 27, 1979 to Dilk;    U.S. Pat. No. 4,373,303 entitled “In-ground trailer post assembly” issued Feb. 15, 1983 to Stratichuk;    U.S. Pat. No. 4,459,832 entitled “Trailer hitch lock” issued Jul. 17, 1984 to Avrea et al;    U.S. Pat. No. 4,538,827 entitled “Ball hitch trailer lock” issued Sep. 3, 1985 to Plifka;    U.S. Pat. No. 4,577,884 entitled “Trailer hitch” issued Mar. 25, 1986 to Harris;    U.S. Pat. No. 4,756,172 entitled “Trailer lock” issued Jul. 12, 1988 to Weaver;    U.S. Pat. No. 4,774,823 entitled “Trailer hitch lock” issued Oct. 4, 1988 to Callison;    U.S. Pat. No. 4,836,570 entitled “Trailer hitch” issued Jun. 6, 1989 to Lopez et al;    U.S. Pat. No. 5,087,064 entitled “Anti-theft and safety device for a ball and socket trailer hitch” issued Feb. 11, 1992 to Guhlin;    U.S. Pat. No. 5,094,423 entitled “Trailer security device and method” issued Mar. 10, 1992 to Almquist et al;    U.S. Pat. No. 5,195,339 entitled “Security device for a trailer hitch or similar article” issued Mar. 23, 1993 to Nee et al;    U.S. Pat. No. 5,351,511 entitled “Trailer kingpin locking device” issued Oct. 4, 1994 to Bernier;    U.S. Pat. No. 5,584,495 entitled “Trailer hitch locking assembly” issued Dec. 17, 1996 to Mason;    U.S. Pat. No. 5,700,024 entitled “Coupler locking device and method” issued Dec. 23, 1997 to Upchurch;    U.S. Pat. No. 5,775,139 entitled “Trailer hitch lock” issued Jul. 7, 1998 to Sellers;    U.S. Pat. No. 5,873,271 entitled “Trailer vehicle security device” issued Feb. 23, 1999 to Smith;    U.S. Pat. No. 6,070,441 entitled “Trailer hitch security device” issued Jun. 6, 2000 to Bernstrom;    U.S. Pat. No. 6,406,052 entitled “Secure trailer hitching post” issued Jun. 18, 2002 to Bale; and    GB 2 126 549 entitled “Trailer security device” published Mar. 28, 1984 in the name of Roberts.